Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Wind turbine rotor blades generally include a body shell formed by two shell halves of a composite laminate material. The shell halves are generally manufactured using molding processes and then coupled together along the corresponding ends of the rotor blade. In general, the body shell is relatively light-weight and has structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. To increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner surfaces of the shell halves.
The spar caps may be constructed of various materials, including but not limited to glass fiber laminate composites and/or carbon fiber laminate composites. More specifically, a plurality of plies of composite material are typically laid up in a mold and vacuum infused together to form the spar caps. The ends of the plies, however, can create areas of local stress concentrations, thereby causing the part to delaminate. In addition, the ends of the plies may cause vacuum bag bridging issues which can lead to defects in the resulting part.
Accordingly, there is a need for an improved spar cap that addresses the aforementioned issues. More specifically, a spar cap having an improved layup sequence would be advantageous.